Voltage regulator



Nov. 12, 1940. J. F. KOVALSKY VOLTAGE REGULATOR FiIed May 5,

1939 3 Sheets-Sheet l INVENTOR 3 ESQQ Q has 0 F/g Z WITNESSES:

Joseph f #0 l/a/s/ry ATTORNEY Nov. 12, 1940.

wlmassas: @m f J. F. KOVALSKY VVVVVV ER EEEEEE OR 1 i W U l E r M III INYENTOR Jweph F K 01 0/5/ ATTORNEY Nov. 12, 1940. .1. KOVALSKY VOLTAGE REGULATOR Filed May 5, 1939 3 SheetsSheet BCDEF D/sfance m M/M'mefers /0 /5 0/5 fan ce /'r1 Mi/h'me fers muxo /0 /5 0/5 fance in Mf/fimefera lNVENTOR Jofiep/z FK01 0/5/g/ WITNESSES; @716 BY away, ATTORNEY Patented Nov. 1940 UNITED STATES. PATENT OFFICE young: 2122mm I Joseph EKova-lskyfllnrtle Creek, Pa.,assignorto Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 5,1939, serial No. 271,910-

' v 11 Claims. (cl. 111-229) This invention relates to regulating apparatus and particularly to regulators of the, rheostatic type such as are desirable for controlling the excitation of the field winding of a dynamfo-elec tric machine, although the invention is not limited to this application.

In a regulator of the character contemplated, a rheostatic control device is employed including a regulating resistor and aleaf spring assembly which may consist of a number of bronze leaf springs corresponding ends of which are clamped in an insulating support and connected to spaced points along the regulating resistor that is connected in the c-ircuit to be controlled.

The unclamped or free ends of the leaf springs which are movable carry contact buttons and are so arranged that the ends of the successive springs of the group overlap the preceding spring.

A stop is provided having a sloping surface that engages the ends of the springs to limit their movement in one direction and,.to position them in spaced relation except as actuated from such limiting positions by operation of a driving memher that raises successive leaf springs from enga'gement with the stop into circuitclosing engagement with the next adjacent spring of the group. 7

In regulators of this character the total load on the driving member includesthe load of the main spring which opposesthe pull of an armature that is actuated by a magnet energized in accordance with the value of tliequantlty being of the regulated, and also the loadof as several leaf springs as may be raised from en- -gagement with the.stop\by the driving member and which bias the drivingjmember in adirec- V tion contrary to the'force exerted by the main Pring. p

The main spring load varies substantially as 40 a straight line-function of the podtion of the driving member, while the load of the group of leaf springs or contact load varies substantially as some higher power of the change in position of the driving member. As the required current carrying .capacity of a leaf spring rheostat de' load curve and the pull curve corresponding to a slight drop in the regulated'voltage. with a corresponding increase in field excitation so that the position of the driving member will remain stationary in a definite position for any partic- 5 ular value of voltage throughout its intended range of operation.

It is, therefore, an object of myinvention to provide aregulator of thecharacter indicated in which the pull characteristics of {the electro- 10 magnet operating it corresponds substantially to the load characteristics of the magnet armature over the same range of movement.

- Other objects and advantages of the invention will be apparent from the following description 15 of a preferred embodiment of the invention, reference being had to the accompanying drawings in which: t

Figure l is a diagrammatic view of apparatus and circuits organized in accordance with the invention;

Fig. 2 illustrates load curves corresponding to those of a single leaf spring rheostat element.

Fig. 3 is a plan view of a leaf spring assembly constituting one resistor varying element of the rheostat with the outer ends of the several leaf springs positioned against the stop.

Fig. 4 is a plan view of the same leaf spring assembly with certain of the circuit controlling members raised from engagement with the stop 30 and into circuit closing engagement with one another. g e

Figs. 5, 6 and 7 are urves-showing the characteristic performance of the regulating structures illustrated in the other figures of the 35 drawings. g I

Referring particularly to Figure 1 of the drawings, a regulator system is illustrated that is arranged for controlling the voltage of a generator I having an armature winding 2 connected to 0 supply circuit conductors 3 and l, and a field winding! connected in shunt relation to the armature winding through a circuit including conductor i. regulating resistors 1 and 8, conductor 9, field rheostat [2, the field winding 5 and con- 45 ductor H. The excitation of the field windin 5 is controlled rby two rheostatic devices I 5 and I which, in addition to the regulating resistors 1 and I, each include a resistor varying element comprising a plurality of leaf springs or circuit gcontrollingmembers for varying the effective value of the resistors 'l and 8. The rheostatic 1 device ll includes a pluralit of leaf springs ll arranged in a stack and connected by conductors it to a plurality of spacedpoints along the resistor 1. The fixed ends of the leaf springs II are insulated from one another by strips of insulating material I! and are retained between pressure plates 2| and 22 by a suitable clamping means 23. The other ends of the leaf springs 11 are free to move and have a biasing force toward the left as viewed in Fig. 1 into engagement with a stop block 24 of insulating material for limiting their motion toward the left and forspacing the free ends of the leaf springs or circuit controlling elements l1 so that contact buttons 25 carried thereby are out of conducting engagement with the buttons carried by adjacent leaf springs when the ends of the springs are in engagement with the stop 24. The leaf springs are adapted to be moved by a driving member 26 into circuit closing engagement to shunt portions of the resistor 1. The driving member 26 is carried on a moving arm 21 that is pivotally mounted at 28 and is biased in one direction about the pivot point by a main spring 29 which acts in opposition to an armature 3| shown as positioned on the opposite end of the lever 21 and actuated by a magnet 32 energized by a winding 33. The winding 33 is connected to a circuit that is energized in accordance with the quantity to be regulated, which, in the present application of the invention, is the voltage between conductors 3 and 4. This circuit extends with conductor 3 through conductor 34, voltage adjusting rheostat 35, conductor 36, winding 33, conductor 31, the secondary winding 33 of a stabilizing transformer 39 and by conductor 41 to the supply circuit conductor 4. The primary winding 42 of the transformer 39 is connected by conductors 43 and 44 across the field winding 5 of the generator l.

The rheostatic device I6 is similar in general construction to the rheostatic device 15, and comprises, in addition to the resistor 6, a plurality of leaf springs 45 forming a stack spaced from one end by strips of insulating material 46 and connected by conductors 41 to spaced points along the resistor 9. The fixed ends of the leaf springs 45, together with the insulating strips 46, are held tightly between clamping plates 49 and 49 by clamping means 52. springs 45 are free to move and have a biasing force toward the right asviewed in Fig. 1 into engagement with a stop block 53 for limiting their motion in one direction and for spacing the contact members 54 carried adjacent their free ends out of. engagement with one another, except as moved into engagement by a driving member 55 carried by the lever arm 21, which raises an increasing number of the springs 45 out of engagement with the stop 53 upon movement toward the left as viewed in Fig. 1. Stops 56 and 51 are provided on the lever 21 for limiting the movement of the lever arm 21 in the one or the other direction to positions corresponding to the range of operation of the leaf springs l1 and 45.

The rheostatic device I. differs from the rheostatic device 15 in that the contact members 54 carried by the leaf springs 45 are of insulating material and the means for closing the circuit betweenthe members 45 is the surface of the stop 53 engaged by the members 45 'and which is of electrically conducting material.

The leaf spring assembly of the rheostatic devices 15 and I6 may correspond substantially to the construction disclosed in greater detail in the copending application of C. R. Hanna et ai. Serial No. 203,876, filed April 23, 1938, for Regulators and assigned to the same assignee of this appli- The free ends of the leaf of the regulator, so that cation. In that application a single leaf spring assembly was employed similar to that shown for the rheostatic device l5 and in Figs. 3 and 4 of the present application for controlling the effective value of the associated resistor. It will be noted in the present application that the group of leaf springs 11 are so arranged that as the arm 21 moves toward the right as viewed in Fig. l, the driving member 26 causes successive engagement of the contact members 25 to short circuit successive portions of the resistor 1 from the field winding circuit, while the driving member 55 permits engagement of a like number of the leaf springs 45 with the conducting stop 53 and separation of the contact members 54, so as to short circuit a like number of portions of the resistor 8. Movement of the lever 21 in the opposite direction causes an opposite variation in the effective values of the resistors 1 and 8. The biasing forces exerted by the leaf spring assemblies of the two rheostatic devices are similar and are so arranged as to be exerted on the lever 21 in opposite directions.

The core structure provided is shown in the shape of a square C and comprises a winding leg about which the turns of the energizing winding 33 are wound and to the opposite ends of which inwardly projecting core legs are connected termi nating in parallel faces 58 and 59 that are spaced to provide for the armature 3| of magnetic material therebetween to provide a double air gap of substantially constant value independently of the position of the armature 3| within the range of travel required for operating the rheostatic devices l5 and IS. The magnet and operating structure assembly may correspond to that shown in copending application of Ralph A. Geiselman Serial No. 219,527, filed July 16, 1938, for Regulators, and assigned to the same assignee as this application.

Fig. 2 of the drawings shows curves illustrating the nature of the load on the lever 21 when a single rheostatic device such as I5 is employed. The spaces along the abscissa indicate the ,distance of movement of the.drivlng member 26 from a position sufliciently to the left to permit all of the leaf springs l1 to be in engagement with the stop 24. As the driving member 26 moves toward the right from this position, the main spring 29 contracts somewhat so that its load decreases as shown by the curve 62. An increasing number of the leaf springs l1 are moved from engagement with the stop 24 as the driving member 26 moves towards the right and the biasing force of each of these springs increases somewhat with continued movement away from the stop member. The curve 63 shows the increasing force of the group of springs I1 with movement of the driving member. 26. It will be noted that the contact load as shown by the curve 63 is in a direction contrary to the main spring load as shown by curve 62, so that the resultant total force is the difference between these two loads and is shown by the curve 64. The mechanical construction is such that the load variation of the 1 group of leaf springs as shown by the curve 63 is a non-linear variation. The magnetic pull required on the armature 3| to maintain the lever 21 and the driving member 26 in any given position must be equal and opposite to the total load plus a sufllcient differential or drop in pull with increasing position necessary for stable operation the lever 21 will assume a slightly diflerent position for each different energization of the winding 33.

Referring to Fig. 5 of'the drawings, the curve 64 is a characteristic load curve of a rheostatic device similar to l5 including the loading .of the restraining or main spring 29, together with the loading of the resistor varying leaf springs l'l indicated in-pound force for varying positions of the driving member 26 plotted as the amount of movement of the driving member 26 over the operating range corresponding to variations in the effective value of the resistor 1. I

The curves 65 to 12 are a family of curves illustrating the pull of the core 32 on the armature 3| for a. typical rheostatic device over the same range of movement of the driving member 26, each curve representing a particular value of current through the regulator coil 33, such, for example, as from .065 to .105' ampere.

It will be noted that each of the pull curves B5 to 12 corresponding to specific values of coil current intersect the curve 64 at definite angles,

vary from'the value represented by curve H at one extremeend of the-range to substantially the current value represented by curve 66 at the other extreme end of the range. The sensitivity of the regulator, is determined by the amount of departure of the load curve 24 from the current curve II indicated by the shaded portion in Fig: 4. The more nearly the load curve. 64 may be made to correspond to the curve II, the more sensitive the regulator becomes, or the less variation in energization of the regulator exists over the operating range thereof. The curve 13 in Fig. 6 is a sensitivity curve corresponding to the difierential between curves 64 and 1 I in Fig. 5. The position of this curve may be adjusted between say positions 14' and 15 ,shown in d tted lines in Fig. 6 by adjustment of the adjusti g rheostatfifl shown in Fig. 1. The general character of the. curve is, however, not changed by moving its position, and in order to control the sensitivity oi. the regulator, it is necessary to vary the character of loading of theregulator as represented by curve 64 or the character of the magnetic pull as represented by the family ter described wherein a single stack of leaf springs are employed, and particularly if the current carrying capacity is low, so that the total I rent carrying capacity oi. the regulators increases,

' sensitivityorthe regulator becomes poorer due to the increasing valuein the contact load as represented by curve in Fig. 2 eifecting agreater drop in the total loading'i'curve -64 in Fig. 2. As the current carrying capacity ofthe' regulating resistors increases, .it is desirable toemploy a plurality'of rheostatic devices such as of curves 65 to 12. .In a regulator of the charac- G2 or 4 each having its own stack of circuit controllingleal springs, thus limiting the weights handled-by a sin'gle'groupor. stack of suchclrcuit controllingsprlngs to a lower rvaluethan would otherwise. be possible if the entire field creases above the desired value, the increased 7 tact loadcurves of the two stacks or twp resistor of the two sets of leaf springsas represented by 'of oprationas the field resistor varles through- -the armature 3| increases causing the lever 21 50 circuits between corresponding portions of the resistor 1. At the same timethe driving member" .rupting the short circuits through a correspondator voltage is reached the' p ull on the armature some intermediate value of the resistors 'l and 8.

resistance is controlled through a single stack. In accordance with the invention, two stacks are employed, although any multiple of two might be used and are so arranged that the convarying elements oppose one another, so that when an increasing number of the leaf springs of one stack are coming into engagement with their associated stop, an increasing number of the leaf springs of the other stack are being 10 raised from engagement with their associated stop as will be apparent by reference to Fig. 1.

Referring to Fig. 7 of the drawings, the curve 16 represents the contact'load curve of the rheostatic device l5 which is similar in-character to the curve 63 in Fig. 2, and the curve 11 represents the contact load curve of the rheostat device. [6. These two load curves are similar in character, but are so related that the total load the curve 18, shown in dotted lines in Fig. 7, is a straight line, and the sensitivity of the regulator, represented by the curve 19 in Fig. 6, thus becomes a straight line. I l

The pull curve is readily adjustable to vary 25- as a straight line with the result that only the slope of this curve need be' controlled or varied in order to bring the pull curve and the load curve to, match or to'vary with some desired droop in voltage in order to maintain stability out its operating range. l 3 a The operation of the regulator here described is as follows: When the generator I is started, and its voltage is low, the lever 21 will be urged to its'illustrated position by the main or restraining spring 29 in which position the driving mem: ber 26 raises the leaf springs I I from engagement with their associated stop 24 and the driving member 55is moved to a position per-40 mitting the leaf springs to be in engagement with the conducting stop member so that the entire portions of the resistors '1 and 8 are shortcircuited through the two groups of circuit corftrollingleaf springs Hand 45, respectively, per- 45 mitting the energization ofthe field winding 5 to, build up rapidlyimd increase the output voltage of the generator I. I as the voltage of the generator increases toits desired value, the force on to move in a counterclockwise direction 'about the pivot 28 'and move thedriving members 26 and toward the left as viewed in Fig. 1, permitting an increasing number of the springs I! to engage the insulating block 24 to effect separation of 55 the contact members 25 and interrupt the short {5' raises a corresponding number of the springs 45 from engagement with their electrically conducting stop member -53, bringing the insulating. contact members 54 into engagement and interingq'number of portions of the resistor 8, thus correspondingly varying. the'eilective values of'jid the resistors I and -8. When the desired gener- 3| just balances the total spring loading of the arm 21 including the pull of, the spring 2! and the sum of the iorces exerted by as many of the 7 lea! springs l1 and'45 as are outlol' engagement with their associated stop. members effecting It the voltage between conductors 3 and 4 in-J energization of the winding 33 causes an increased pull on the armature 3| to move the driving members 26 and 55 toward the left and interrupt the short circuit through an increasing number of portions of the field controlling resistors I and 8 to increase the resistance in circuit with the field winding and correspondingly decrease the excitation and output voltage of the generator i. This decrease in output voltage causes a like decrease in the energization of the winding and in the pull on the armature 3| to return the driving members 26 and 55 to a position of balance corresponding to the desired generator voltage.

Correspondingly, if the generator voltage decreases below its desired value, the energization of the winding 33 and the pull on the armature 3| correspondingly decreases permitting the spring 29 to move the driving members 25 and 55 toward the right as viewed in Fig. 1 to short circuit an increasing number of portions of the field controlling resistors I and 3 to increase the excitation of the generator field winding 5 and raise the generator voltage to its desired value.

Various modifications and the details of construction of the apparatus and circuits illustrated and described will e apparent to those skilled in the art within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention:

' 1. In a regulator system, a dynamo-electric machine having a field winding, means responsive to a regulated characteristic'of said dynamoelectric machine for governing the excitation of the field winding comprising two rheostatic devices each including a resistor, a plurality of movable spring biased conducting-members connected to separate spaced points along said resistors, and a stop against which the several conducting elements are adapted to rest to limit their movement in one direction, driving means ranged to raise an increasing number of the conducting members oi one of said rheostatic devices from engagement with its associated stop while permitting an increasing number of the conducting members otthe other rheostatic device to rest against its associated stop, and an electromagnet for actuating said driving means.

2. In a regulator system, a dynamo-electric machine having a field winding, means responsive to a regulated characteristic of said dynamoelectric machine for governing the excitation of the field winding comprising two rheostatic devices .each including a' resistor, a plurality of movable spring biased conducting members conn'ected to separate spaced points along said resistor, and a stop against which the several conducting elements are adapted to rest to limit their movement in one direction, driving means for actuating said conducting members and arranged to raise an increasing number 0! the conducting members of one of said rheostatic devices from engagement with its associated stop while permitting an increasing number of the conducting members oi the other rheostatic device to engage its associated stop, the conducting members of one of said rheostatic devices bein arranged to short circuit portions of its associated resistor when raised from engagement with its associated stop and the conducting arranged to short circuit portions of its associated resistor when in engagement with its assofor actuating said conducting members and ar-- members of the other rheostatic device being ciated stop, and an electromagnet energized in accordance with the quantity being regulated for actuating said driving means.

3. In a voltage regulator for a dynamo-electric machine having a field winding, means responsive to the regulated voltage for governing the excitation of said dynamo-electric machine comprising a pair of rheostatic devices each having a field regulating resistor, a plurality of circuit controlling members connected to separate points along said resistor, and means for biasing the circuit controlling members to predetermined spaced positions, the circuit controlling members of one of said rheostatic devices being arranged to short circuit the interconnected portions 01' their associated resistor when in said spaced positions and the circuit controlling members of the other of said rheostatic devices being arranged to short circuit the interconnected portions of their associated resistor when actuated from their spaced positions, electroresponsive means arranged for progressively and oppositely actuating said circuit controlling members to and from said spaced positions, a restraining spring for opposing the operation of said electroresponsive means, an energizing circuit for the electroresponsive means and means for applying a voltage to said circuit that is a measure of the regulated voltage.

4. In a voltage regulator for a dynamo-electric machine having a field winding, means responsive to the regulated voltage for governing the excitation of said dynamo-electric machine comprising a pair of rheostatic devices each having a field regulating resistor, a plurality of circuit controlling members connected to separate points along said resistor and biased to predetermined spaced positions, the like circuit controlling members of the two rheostatic devices being biased in opposition to one another to predetermined spaced positions, electroresponsive means including an armature for progressively and simultaneously actuating the circuit controlling members of the two rheostatic devices to correspondingly vary the short circuit portions of their associated resistors.

5. In a voltage regulator for a dynamo-electric machine having a field winding, means responsive to the regulated voltage for governing the excitation of said dynamo-electric machine comprising two field regulating rheostat devices each having a resistor and a group of circuit controlling members connected to spaced points along their associated resistor and biased to spaced positions. the circuit controlling members oi the two groups having like varying load-with-position characteristics, driving means for actuating the circuit controlling members for correspondingly, controlling the eflectlvevalues o! said-resistors, the biasing forces acting on the two groups of circuit controlling members being arranged to exert op posing forces on said driving means, a restrainin spring for biasing the driving means in one direction, electroresponsive means including an armature for biasing the driving means in the opposite direction, an energizing circuit for the electro-responsive means and means for applying a voltage to saidcircuit that is a measure of the quantity being regulated.

6. In a regulator system, in combination, a circuit to be controlled, two automatic rheostatic devices connected in said circuit and each including a resistor, a plurality of conducting members connected to separate points along said resistor, stop means for spacing the conducting members 7 2,221,587 relative to adjacent conducting members when actuated to the limit of movement in one direction permitted by the stop means, the relative movement of said contact members and said stop means being unrestricted in one direction, and control means including a movable element for actuating said two automatic rheostatic devicesfor varying theeffective values of their associated resistors, the conducting members of one of said rheostatic devices being arranged to short circuit portions of its associated resistor when raised from engagement with its associated stop means and the conducting elements of the other rheostatic device being arranged to short circuit portions of its associated resistor when in engagement with its associated stop, and an electromagnet energized in accordance with the quantity being'regulated for actuating said control means.

7. In a regulator system, in combination, a circult to be controlled, two rheostatic devices in said circuit each including a' resistor and a group of circuit controlling members connected to spaced points along their associated resistor and biased to spaced positions, the circuit controlling members 01 the two groups having like varying load-with-positioncharacteristics, driving means for actuating the circuit controlling members for correspondingly controlling the efiective values of said resistors, the biasing forces acting on the 30 two groups of circuit controlling members being arranged to exert opposing forces on the driving means, a restraining spring for biasing the driving means in one direction, electro-responsive means including an armature for biasing the driving means in the opposite direction, an energizing circuit for the electroresponsive means and means for applying a voltage to said circuit that is a measure of the quantity being regulated.. I 40 8. In a regulator system, in combination, a circuit to be controlled, two rheostatic devices connected in serlesin said circuit each including a resistor, a plurality of circuit controlling members connected to separate points along said resistor 45 and biased to predetermined spaced positions, and

driving means for actuating said circuit controlling members, the like circuit controlling members of the tworheostatic devices being biased in opposition to one another to predetermined spaced 50 positions, electroresponsive means including an armature for operating the driving members for progressively and simultaneously actuating the circuit controlling members of the two rheostatic devices to correspondingly vary the short circuit 55 portions of their associated resistors.

9. In a regulator system, in combination, a circuit to be controlled, two rheostatic devices connected-in series in said circuit each including a resistor, a plurality of circuit controlling members 50 connected to separate points along said resistor,

static device to rest against its and means for biasing the circuit controlling members to predetermined spaced positions, the circuit controlling members of one of said rheostatic devices being arrangedjto short circuit the interconnected portions of their associated resistor when in said spaced positions and the circuit controlling members of the other rheostatic device being arranged to short circuit the interconnected portions of their associated resistor when actuated from their spaced positions, electroresponsive means arranged for progressively and oppositely actuating said circuit controlling members to and from said spaced positions, and an energizing circuit for energizing the electroresponsive means in accordance with variations in the quantity being regulated.

10. In a regulator system, in combination, a circuit to be controlled, two rheostatic devices connected in series in said circuit each including a resistor, a plurality of movable spring biased conducting members connected to separate spaced points along said resistors, and a stop against which the several conducting elements are adapted to rest to limit their movement in one direction, driving means for actuating said conducting members. and arranged to raise an increasing number oi the conductingmembers of one of said rheostatic devices from engagement with its associated stop while permitting an increasing number of the conducting members of I the other rheostatic device to engage its associated stop, the conducting members .of one of said rheo static devices being arranged to short circuit portions of its associated resistor when raised from engagement with its associated stop and the conducting members of the other one of said rheostatic devices being arranged to short circuit portions of its associated resistor when in engagement with its associated stop, and an electromagnet energized in accordance with the quantity being regulated for actuating said driving means.

11. In a regulator system, in combination, a circuit to be controlled, two rheostatic devices connected in series in said circuit each including a resistor, a plurality of movable spring biased conducting members connected to separate spaced points along said resistors, and a stop against which the several conducting elements are adapted to rest to limit their movement in one direction, driving means for actuating said conducting members and arranged to raise an increasing number of the conducting members of one of said rheostatic devices rrom engagement with its associated stop while permitting an increasing number of the conducting members of the other rheo- I stop, and an electromagnet for actuating said driving means.

J OBEPH I". KOVALBKY. 

